The present invention is concerned with a device for assembling two pieces, which are to be coupled and uncoupled, without any special tools.
More particularly, this assembling device is designed for assembling two pieces, of which one includes a skirt extending, in the assembled position, inside the cavity of the other piece.
The present invention is concerned, more particularly, with a watch case, water-tight or not, wherein the assembling of the middle piece and of the bottom piece is achieved with an elastic segment.
Such water-tight watch cases are known from the document CH 362 985 which describes the assembling of the bottom piece with the middle piece of the case by means of a radially expandable segment including radial protrusions designed for co-operating with parts of the bottom piece. This segment is carried by the bottom piece and is designed for a partial engagement into a oblique groove of the middle piece. To close the case, one has to position the bottom angularly with respect to the middle piece, assemble the two pieces together and then operate a relative rotation thereof. In this manner, the radial protrusions of the elastic segment are displaced radially by said bottom piece to cause an expansion of the segment which extends into the oblique groove of the middle piece and to produce an axial tightening of the bottom piece against the middle piece.
This known water-tight watch case suffers major drawbacks. Firstly, the need to adjust the angular position of the bottom piece with respect to the middle piece, before they can be assembled together. Secondly, the need to carry out on the middle part complicated machining operations, in particular for forming the oblique groove. Finally, the need for the segment to be stressed in the water-tight closed position of the case, which causes a rapid wear of this segment.
The aim of the present invention is to provide a watch case wherein the assembling of the bottom piece with the middle piece is ensured by an elastic segment, but which obviates the above-mentioned drawbacks, i. e. wherein the positioning of the bottom piece into the middle piece can be carried out in any relative angular position of these two pieces, wherein the machining operations are simple to carry out and wherein the elastic segment is in an unstressed rest position when the case is in its closed position.
The object of the present invention is an assembling device, in particular for a watch case, which includes a middle piece and a bottom piece assembled through an elastic segment and which is characterised by the features set out in claim 1 and in the dependent claims.